We propose to study both theoretically and experimentally the molecular dynamics of polynucleotides with the aim of understanding the mechanisms that produce changes of conformation. We plan to investigate the role of nucleotide sequence, effect of absorbed water, addition of salt on the normal modes of polynucleotides. We shall also study the f.i.r. spectrum of nucleotides, nucleosides and ribose and compare their calculated and measured spectra. This will provide information with which we can compare intermediate steps of the calculation of the vibrational spectrum of polynucleotides. We shall also attempt a double resonance experiment aimed at the direct measurement of the relative amplitudes of vibrations of several atoms that oscillate at the frequency of one of the normal modes of the molecule.